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That's an excellent question, and I may not be the best qualified to answer it with respect to cancer rates, but I can describe the atmospheric science at least. The ozone "hole" forms from chlorofluorocarbons (CFC's) in the atmosphere, which were used as refrigerants and propellants. They're very stable in the lower atmosphere and can persist for decades there. When they eventually make it to the mid-atmosphere they are broken down into radicals that are transported to the poles as reservoir species. At the poles, under the right conditions, they can destroy ozone quite effectively in the spring when the sun comes out. The main ozone hole occurs over the Antarctic in the southern hemisphere spring, although a smaller one does occur over the Arctic as well. So, most people, unless they live at very high latitudes in the extreme north or south, are not affected by the lack of a protecting ozone layer over the poles. CFC's have been banned at this point in most countries, but because of their long lifetimes and outgassing from old refigerators, etc., the ozone hole is not expected to fully recover until about 2065 or so. In short, although we will have ozone depletion for many years to come, it's generally contained to extreme latitudes and shouldn't, in my unqualified opinion, have a large effect on cancer rates.

It depends what aerosols we are talking about here. Most people think of spray cans when they hear aerosols. In that case, yes, they do warm up the atmosphere because CFC's, which are pretty strong greenhouse gases, were traditionally used as the propellants in spray cans. The aerosols to which I am referring, however, are tiny particles suspended in the atmosphere, often referred to as particulate matter. In this case, most of the particles primarily scatter solar radiation, some of it back into space, thereby cooling the surface and counteracting greenhouse warming somewhat.

No, an astronomer studies celestial bodies (stars, planets, galaxies, etc.) in space. My job as an atmospheric chemist is focused on just Earth's atmosphere. However, there are many atmospheric chemists who also study the atmospheres of other planets to try and determine what their atmospheres are made of and whether there may be life on the planet.

This may seem kind of obvious, but atmospheric chemists study the chemistry of the atmosphere. The atmosphere is made up of lots of atoms, molecules, charged particles, and particulate matter. Most of these species are too small to see, but they are constantly being transported and transformed through chemical reactions with other species and through interactions with sunlight. The chemistry of the atmosphere is very important because we must breathe it to survive, and also because its composition drives our climate, or what the weather is like over long periods of time. Atmospheric chemists like me study what the chemistry of the atmosphere is like now, what it might be like in the future, and how any changes may affect human health and the climate.

I think my job is pretty fun. I do like people too. I have to interact with people all the time. I'm a professor, so I'm constantly interacting with students and colleagues at my university. And as a researcher, I interact with really cool people from all over the world who study similar things as me.

Right now, we have two cats. We had a Chinese Water Dragon too, but she didn't do so well. Good thing I'm not a biologist! :)

It sounds like, by your use of the term aerosols, that you are referring to the propellants used in spray cans. These became infamous because of the CFC's that were used as propellants that led to ozone destruction and the formation of the ozone hole. When I refer to aerosols in my research, I am referring to particulate matter in the atmosphere, which can be of human or natural origin - anything from dust or sea salt to particles from vehicular emissions and power plants. Unfortunately, aerosol is a general term that means a suspension of particles in a gas, so could refer to any number of things. Anyway, now that we've cleared up that confusion, I will say, yes, aerosols (whether you mean propellants or atmospheric particles) could change the color of the sky. In fact, they already do! Any atmospheric constituent that scatters visible light will change the color of the sky. That's why the sky is blue! Because molecules in the atmosphere preferentially scatter the shorter, blue wavelengths of light. And aerosols (particulate matter in this case) also change the color of the sky. When the sky looks nice and hazy (especially when it's really hot and humid in the summertime), that's from particles in the atmosphere scattering sunlight. Because the particles come in many different sizes, they scatter all visible wavelengths, causing a whitish haze. That's why clouds look white too, because they scatter all visible wavelengths of light. I hope this answers your question.

Wow, I have to put on my weather weenie hat now. :) There are six basic ingredients to hurricane formation:
1. High sea surface temperatures that extend pretty deep below the surface - these "feed" the strong convection necessary for hurricanes to develop from the evaporation of warm water at the surface and the instability of the atmosphere that is created, with warm temperatures below and cooler temperatures aloft. The warm sea temperatures must go deep, however, because the strong winds will stir up the water. If it's too cool below the surface, that could be the end of the hurricane.
2. Atmospheric Instability - which is fed by warm sea surface temperatures. Warm air at the surface will be more buoyant than cooler air aloft and will rise rapidly. This lift is necessary for the development of strong thunderstorms in a hurricane.
3. Moist air in the middle troposphere (~8-10 km) - this helps to maintain positive buoyancy of air in a hurricane. If the air is too dry in the mid-troposphere, when it gets sucked into the hurricane, it will cause evaporation and cooling of the air, which will cause that air to sink, and sinking air's not good for a hurricane.
4. Weak vertical wind shear - wind shear is a change in wind speed or direction with altitude. If wind shear is too strong, it will decouple the top of the storm from the bottom and kill the hurricane.
5. Rotation - a hurricane cannot form too close to the equator (less than about 5 degrees latitude). Without going into detail about the Coriolis force, hurricanes need rotation. If you get too close to the equator, the Coriolis force is too weak and you don't have the necessary rotation to form a hurricane.
6. Cyclonic spin - easterly waves, which are tropical disturbances that form north of the equator over Africa and move westward across the tropical North Atlantic, are the "seeds" that provide the low level cyclonic (counter-clockwise) spin for many of the hurricanes that form over the North Atlantic (the ones that affect us!).

Thunder happens when lightning heats the atmosphere to extremely high temperatures - about 50,000 deg F. That's a lot hotter than the surface of the sun! Such extreme and rapid heating causes the air around the lightning to expand explosively. This explosive expansion of the air creates a sound wave that propagates in all directions at the speed of sound - and voila, you have thunder!

Either way, I would recommend my job to others. I love what I do. It's great because I get to do something different every day and feel like I'm always solving puzzles to find the best answer. You could absolutely do this job with bad eyesight. No vision tests required for atmospheric science!

That's a really good question. I knew that I wanted to go into some type of environmental science, as I was interested in the environment, loved the outdoors, and really enjoyed science and math. I originally thought that I would be a biologist, but I thought biology was pretty boring. Then I started taking chemistry and knew that I had found the field for me. When I went to graduate school, though, I still hadn't settled on atmospheric chemistry. I just knew that I would do some type of environmental chemistry. It just so happened that the research group that I was most interested in working with (for a variety of reasons) was an atmospheric research group. The rest is history, as they say.

Ambient particulate matter is particles that are suspended (floating around) in the atmosphere. They come from lots of different sources, both natural and man-made, and can include things like dust and sea-salt as well as smoke from forest fires and particles that form from vehicle and industrial emissions. Some, like dust and smoke particles, are big enough or dense enough to be visible to the naked eye, but most are too small to see, even though we're breathing them in all the time. Often times, though, you can see a haze in the atmosphere, especially if you look toward the horizon. This haze is caused by the particles in the atmosphere, or ambient particulate matter.

Great question...and it depends. If it's a large enough volcanic eruption, and the eruption is directed straight up, the particles from the eruption can make it into the stratosphere (above about 15-18 km) and stay in the atmosphere for years. That's what happened with the El Chichon and Pinatubo eruptions in recent decades. Eruptions of this scale and type actually cause a global cooling, much like a nuclear winter would, because the particles in the stratosphere block incoming sunlight. These are pretty special eruptions, though. Even most large eruptions, such as Mount St. Helens, don't make it into the stratosphere because the direction of the eruption is not right. Mount St. Helens was a massive eruption, but it erupted more to the side, essentially blowing the side off of the volcano, rather than going straight up. For those eruptions that don't make it into the stratosphere, volcanic particles emitted lower in the atmosphere will only last an average of about a week before they get rained out.

What are your projections in terms of Earth's habitability as time goes on?
Do you think colonization on other planets is a good solution to global warming and the gradual weakening of the Earth's ecosystem?

Whew, those are some serious questions, and way outside of my area of expertise, but I'll try and answer as best I can regardless. As far as habitability goes, that depends on your perspective. If you're looking at it from a global perspective, I think it will be quite some time before Earth as a whole is inhabitable. However, if you're living in a low-lying coastal region or are a polar bear or some other species living in a threatened environment, habitability may be lost in the next century.

Now for colonization of other planets. I don't think that's a solution at all to climate change, unless you're talking about removing the entire human population from Earth. Even that, though, would probably cause more damage than staying, at least for the foreseeable future, if you think about all of the nuclear facilities and the like that would cause catastrophic damage to Earth if abandoned. I think the colonization of other planets is a very cool idea from an intellectual perspective and probably necessary down the road for the survival of the human species, but I think we're a loooong way from realizing what is currently only a reality in Sci-Fi books and movies.

In general, it all comes down to energy balance. When the distribution of energy becomes imbalanced in the Earth-atmosphere system, the energy will be redistributed as it tries to restore a balance. Sometimes that redistribution of energy can happen very quickly if there is a large imbalance.

More specifically, when the atmosphere becomes highly unstable, severe weather, or storms, may occur. The instability happens when there is a large difference in the temperature of the warm air near the surface and cooler air aloft. Warmer air is more buoyant than cooler air, and if there is a large temperature difference, the warmer air may rise very rapidly. If the warm air is also moist, it will rise even more and will provide the precipitation for severe storms once the air that has risen cools enough to condense out the water vapor as liquid or solid water. That rapid rising of air (redistributing the higher energy, warm air near the surface up into the atmosphere) and formation of precipitation as the warm, moist air cools higher up in the atmosphere provide the ingredients for severe weather. And voila, you have a storm!

You mean besides being carried off to Munchkinland in Oz? Seriously, it's actually very difficult to know for sure. Making a measurement inside of a tornado is nearly impossible and no reliable measurements, as far as I know, have actually been made within a tornado. That said, the air pressure inside of a tornado will be considerably lower than outside, probably dropping by 100 millibars or more (around 10% lower than normal). It would be roughly the equivalent of the air pressure drop if you climbed a 3000 ft. mountain. I wouldn't advise trying it though. :)

That's a tough one. I enjoy so many things about my job. I think the thing that I really enjoy most, though, is the freedom to design my own experiments to try and better understand the world around me. And then when you discover something new and interesting - it doesn't get much better than that!

Science has given us everything from modern medicine to modern appliances. In general, though, the scientific method has given us a specific way to look at the world around us and to figure things out in an analytical manner. In my opinion, everybody should have a good basis in science for a couple of reasons. One, because science teaches us how to approach problems (any problems) in an analytical manner. Two, because without a foundation in science, people are not able to understand the specific problems that plague us today and that will continue to plague us into the future. Take climate change, for example. If people don't understand the issues, they are not able to make informed decisions to try and mitigate the problems. Other examples include renewable vs. non-renewable fuels, stem cell research, and many others.

Hopefully not anytime soon. Seriously, I don't think the planet itself has much to worry about. It will most likely persist for at least a few billion more years. The life that currently inhabits the planet (including us!) is another matter altogether. We're already seeing the impacts of climate change and will continue to do so into the future. Species that live in fragile ecosystems are already being impacted or will be in the near future and will suffer the most in the near term. However, exactly what the consequences will be to most species is very difficult to say. Climate change is like conducting an enormous, planetary scale experiment. We have hypotheses as to what the impacts will be, but the uncertainty is very large and it's difficult to say exactly how many areas and species will ultimately be affected.

In general, particulate matter of any size is not particularly good for humans. However, particulate matter that is 2.5 micrometers (a micrometer is one millionth of a meter) or less will make it past our nasal passages and lodge in our lungs, which tends to have the most negative impact on human health. For the most part, in this country, because of regulations on emissions over the past few decades, this size particulate matter is decreasing. But, because of rising global temperatures, emissions or organic (carbon-based) compounds from plants may increase. These compounds can also form small particles in the atmosphere, so it's difficult to predict what will happen with the overall amount of particles in the atmosphere. Most atmospheric particles primarily scatter solar radiation, leading to a net cooling, which can offset greenhouse gas warming somewhat. So, if we decrease the amount of particles in the atmosphere, this could actually exacerbate the greenhouse warming that we're currently experiencing. But if plant emissions increase, leading to greater particle formation, this could again offset some of the warming. As you can probably tell, it's a very complicated issue that we're just beginning to understand.

That said, in many developing countries around the world with rapidly expanding economies and regulatory policies that are lagging very far behind, emissions are also increasing, leading to an increase in the amount of particulate pollution. In general, atmospheric particles only last for about a week before being rained out, so particulate pollution is much more regional in nature than most greenhouse gases, for example. This adds to the difficulty in trying to understand the climate (and health) impacts of particulate matter on a global scale.

The most important thing we can probably do is to cut down on our carbon emissions. We can do this in a couple of ways. One way is by conserving fuel. This is something that we can all do by making some simple changes like using compact fluorescent light bulbs instead of incandescent light bulbs and remembering to turn off the lights when leaving a room, turning down the heat in your house (or using a programmable thermostat), walking and biking instead of driving (which is also good for you), etc. The other way is to use less fossil fuels and more clean, renewable fuels, like solar and wind power. This is something that everyone can do as well, but that also needs to be dealt with on a larger scale by the leaders of today. Scientists can provide the evidence necessary to allow politicians to make the most informed decisions possible, but citizens can also let their representatives know that it's time to take action. It's also important to remember that the atmosphere is fine either way, it's the plants and animals that rely on the atmosphere that are suffering.

Hi Caroline and Abby,
In every cloud, there are updrafts (where the air moves up) and downdrafts (where the air moves down). If the top of a cloud is cold enough, a liquid cloud droplet can freeze, making a little ball of hail, as it moves upward in an updraft. As it then moves down in a downdraft, the hail may thaw, but if it's cold enough lower down in the cloud (and below the cloud), the hail may make it all the way to the ground as a frozen particle. Sometimes, after coming down in a downdraft, the hail will then get sucked back into an updraft, adding another layer of ice to it on its journey up through the cloud. This may happen several times, causing the hail to grow with every pass, until eventually it's too heavy and falls out of the cloud. This is when you can get some very large balls of hail!

I like science because I'm a curious person and science gives me the tools necessary to explore the world around me. The type of science I do allows me to work with my hands while solving problems with my mind. I also love the freedom that I have in designing my own experiments to try and answer the important questions facing us today. Most of all, it's fun!

That depends on what you mean by bad. We need particles in the atmosphere to make clouds, so some amount of particles is always a good thing. But, there are naturally occurring particles (sea salt, dust, etc.) and man-made particles. Man-made particles may contain chemical compounds that are harmful to human health. Plus, they are typically smaller than naturally occurring particles. Smaller particles can more easily make it past our nasal defenses and lodge in our lungs, which can lead to serious health issues or even death (in people whose health is already compromised). Also, smaller particles tend to have a larger climate impact because they are closer in size to the most intense wavelengths of light coming from the sun. So, if I had to pick the "bad" particles, I would have to say man-made particles are the worst culprits.

Wow, that's a tough question. Not because I can't think of anything that's intriguing, but because so much of it is intriguing! That's why I love science so much. It's all about being curious about the world around you and trying to figure things out. Everyday there are new mysteries to solve and puzzles to piece together. Sometimes it can get frustrating and feel like you're trying to find your way in the dark, but that moment when things start to come together provides a great sense of accomplishment and satisfaction.

The full answer to that question could probably fill several books (and has!). And most of what we "know" is based on the geological record, meaning that most of the atmospheric formation to date occurred in the very distant past, so we have prevailing theories about atmospheric formation, but can never know for sure. Fortunately, though, I think I can summarize a very simplified version of a theory of atmospheric evolution pretty succinctly. In short, there have been three main stages of atmospheric evolution. The first atmosphere probably consisted of primarily hydrogen and helium after Earth was just formed, as these were the main gases in the solar "dust" from which the planets formed. Early Earth and its atmosphere were very hot just after formation, so most of the hydrogen and helium were traveling very fast and eventually escaped into space. The second atmosphere evolved when Earth was still very young and geologically active. There were many volcanoes that emitted water vapor, carbon dioxide and ammonia. Much of the carbon dioxide dissolved into the oceans. Eventually, simple bacteria evolved that could use the carbon dioxide (together with sunlight - the first photosynthetic activity on the planet!) for energy. The waste product they gave off was oxygen. Carbon dioxide levels continued to decrease as it was used up, and oxygen levels continued to increase as it was emitted as waste. At the same time, the ammonia (NH3) was split apart by photons from the sun, leaving nitrogen and hydrogen. The hydrogen, being so light, eventually escaped into space, as it did in the "first atmosphere". So, over time, the atmosphere that we have today, with lots of nitrogen and oxygen, formed. And there you have it!

I'm not sure they necessarily are. Most atmospheric particles go through phases of wetting and drying out, depending on the relative humidity and whether they get sucked up into a cloud or not. I think it's more a matter of size. In general, the same particle will be larger if it is wet than if it is dry because of the uptake of water. It will often grow larger during this period too if more material is dissolved into the liquid. Smaller particles are typically more of a concern for human health than large particles because they can make it past our nasal defenses and lodge themselves in our lungs. So, that could be a reason that dry particles are more of a health concern than wet ones. Anyway, I hope that answers your question.

Engines, depending on what type (e.g., diesel, four-stroke, two-stroke, etc.), emit carbon monoxide, oxides of nitrogen, volatile organic compounds (VOC's), and particulate matter into the atmosphere. Most of these compounds, if breathed in directly, are not very good for you from a health perspective, but they also have many climate and air quality impacts. Nitrogen oxides and VOC's are the two main ingredients necessary for producing ozone, a strong oxidant that damages cell tissue (both plant and animal) and which is also a greenhouse gas. They can also lead to atmospheric particle formation, thereby having large climate and visibility impacts (together with the particles that were directly emitted).

For both "direct" and "indirect" reasons. Particles directly interact with solar radiation by either absorbing or scatting the light. Most particles primarily scatter solar radiation, some of which is scattered back up into space. Because that solar radiation which was scattered back to space never reaches the surface, particles have a net cooling effect. For mainly absorbing particles (e.g., soot), because they largely absorb solar radiation, they can heat up the layer of atmosphere where they reside. This can actually burn off clouds or prevent them from forming in the first place. Speaking of clouds, particles also have an indirect effect on the climate. Clouds need particles to form. The particles provide nucleation sites for the water vapor to condense onto and form cloud droplets. When we add a more particles to the atmosphere, this can affect the size of cloud droplets, the opacity of clouds (how optically thick a cloud is), their potential to form rain drops, and cloud lifetimes. Because clouds have such a large impact on the water cycle and climate, aerosols do as well, just indirectly.

Dolphins are mammals, just like us. That means they need to breathe air like us. They go to the surface of the water so that they can breathe. Plus, I'm sure they also enjoy playing in the sunshine just like us!

Gases actually make up the atmosphere. Gravity holds the gases close to the surface, creating the atmosphere as we know it. The gases are emitted into the atmosphere from different sources. Hydrogen and helium were the main gases in the solar "dust" from which the planets formed. Early Earth and its atmosphere were very hot just after formation, so most of the hydrogen and helium were traveling very fast and eventually escaped into space. Then, volcanoes started emitting water vapor, carbon dioxide and ammonia. Much of the carbon dioxide dissolved into the oceans. Eventually, simple bacteria evolved that could use the carbon dioxide (together with sunlight - the first photosynthetic activity on the planet!) for energy. The waste product they gave off was oxygen. Carbon dioxide levels continued to decrease as it was used up, and oxygen levels continued to increase as it was emitted as waste. At the same time, the ammonia (NH3) was split apart by photons from the sun, leaving nitrogen and hydrogen. The hydrogen, being so light, eventually escaped into space, as it did early on. So, over time, the atmosphere that we have today, with lots of nitrogen and oxygen, formed. And there you have it!

Are there many different kinds of Atmspheric Chemists, or is there just your job? I was also wondering how long it takes to get your information for your research. Does it take a day, or can it take a week or more?

Is it viable to enrich the oceans with carbon-fixating bacteria to reduce the amount of Co2 in the atmosphere, or should we use another method? Will the atmosphere heal over time or will we enter something similar to the Eocyne Period?

HELLO for me it is very interesting to learn about what you do for a living...... so you are like a scientist? now when im in school im not very good at science but it is very interesting to learn about. How old were you when you were starting to be interested in science?!? thanks and i hope you respond.